High vacuum pump



April 4, 1939. K. c. D. HICKMAN HIGH VACUUM PUMP Filed May 18, 1957 4 Sheets-Sheet 1 FIG];

FIGA.

Kenneth CDHickan INVENT OR.

ATTORNEYS K. c. D. HICKMAN HIGH VACUUM PUMP Filed May 18, 1937 April 4, 1939.

4 SheetsSheet 3 Kenneth CDHicKman I INVENTOR. W

ATTORNEYS April 1939. K. c. D. HICKMAN 2,153,189

HIGH VACUUM PUMP Filed May 18, 1937 4 Sheets-Sheet 4 FIG .13.

Kenneth CDHickman INVENTOR.

ATTORNEYS Patented Apr. 4, 1939- UNITED STATES men VACUUM PUMP Kenneth c. n. Hickman, Rochester, N. 1., as-

signor, by mesnc assignments, to Distillation Products, Inc., Rochester, N. Y., a corporation of a I Delaware Application May 18, 1937, Serial No. 143,305

11 Claims. (Cl. 230-9101) This invention relates to improvements in high vacuum or condensation pumps and, particularly, to condensation pumps adapted to employ mixed organic pumping fluids.

In my co-pending application No. 27,652, flied June 21, 1935, of which this is a continuation-in part, there is disclosed improved forms of condensation pumps. It was disclosed therein that organic pump fluids are mixtures of substances of difierent vapor pressure and that volatile or very non-volatile constituents are present which undesirably aflect the pumping action of the useful components of the pump liquid. It was further disclosed that the pump liquid could be see- 16 regated into useful and non-useful pumping components and that the useful components could be'further segregated into portions of progressively decreasing volatility and caused to perform theirpumping action at appropriate positions in a cascade pump.

It is an object of this invention to provide improved fractionating pumps of the character deis to provide improved fractionating condensa-.

tio'n' pumps of high efficiency and/or pumping capacity. Another object is to provide fractionating condensation pumps having greater simplicity and ease of construction and operation. Other objects'will become apparent from the following description.

My invention will be more clearly understood from the following description and the accompanying drawings wherein I have illustrated sev- .eral embodiments thereof, wherein like numerals refer tolike parts, and wherein: a Fig- 1 illustrates a sectional elevation of one of the forms of fractionating pumps embodying the principles of my invention and having the advantage of utmost in simplicity of constructon due to the use ofcylindrical'elements;

Fig. 2 is a section taken on line 2-2 of Fig. 1'; Fig. 3 is a sectional elevation of a modification of the apparatus illustrated in Fig. 1;

Fig. 4 is a sectional view taken on line of I Fig. 3;

Fig. 5 is a sectional elevation ofa preferred form of condensation pump;

Fig. 6 is a sectional view of the pump of Fig. 5

taken on line 6--6;

Fig. 7 is a sectional view taken on line 11 of 55 Fig. 5; 4

modification of the high vacuum jet system in Fig. 8 is a sectional fragmentary view taken on line 8-8 of Fig. 5;

Fig. 9 is a fragmentary sectional elevation of a Fig- 10 is a sectional elevation of "a pump similar to that illustrated in Fig. 3 but provided with fractionating trays in the low vacuum end for segregation of volatile components;

Fig. 11 is a sectional view taken on line lI-l| 10 of Fig. 10;

Fig. 12 is a sectional elevation of a conventional condensation pump provided with 'fractionating features and a flash boiler, and arranged to work in conjunction with a cascade fractionating conla densation pump;

Fig. 13 is a modification of the apparatus illustrated, a flash boiler centrally located in the jet system being provided;

Fig. 14 is a sectional view on line |4-l6 of 20 Fig. 13. v

Referring to Figs. 1 and 2, reference number 3 designates an approximatetly cylindrical main pump casing attached to a flange '4 at the low pressure end and integral with a plate 5 at the high pressure end, which plate is connected to a conduit 6 leading to a backing pump (not shown). Numeral, I designates a eonduit detachably connected to flang'e 4 and which connects pump casing 3 with the receptacle or system to be evacuated. Numeral I 6 designates a plurality of half moon-shaped plates integral with the base of conduit 6 and which serve to fractionate and segregate the most volatile components of the pump fluid, which may be intermittently withdrawn 3 by way of conduit 11. e

Numeral 8 designates an approximately cylindrical casing located inside the main casing 3 and split at the base to form two supporting ribs 9 and II) which rest upon the bottom of main casing 3 and serve to support casing 8 and partition the space inside casing 8 from the annular space formed between the outside of casing 8 and the inside of casing 3. The portion of easing 8 located in the high vacuum end of the pump is constricted to form a cir ular opening II which is covered by an umbrella type of jet I2. At spaced intervals within casing .8 are located a series of partitions 13, I4 and I5 which are integral with the walls of casing 8 and with supporting members 9 and I0 and which extend to the base of main casing Sand divide casing 8 into a series of compartments A, B, C and D. In the base of compartments B and C are located a plurality of staggered baifles l8 which serve to 5 which terminate at the supporting members 9.

Reference numerals 26, and 3| designate series of openings in the wall of casing 8 located under V the jet formed by flanges 26, 21 and 28, respec- .tively, and preferably are of decreasing diameter from the low to the high vacuum side of the, pump, as shown. Reference numeral 32 designates a'body of pumping fluid which rests in the base ofthe main casing 3 and is divided into a plurality of separate pools of fluid by partitions l3, II and I5. The partitions are provided with a seriesof notches 33, '34 and 35 at the base, which allow flow of liquid from one compartment to another, but which substantially prevent the flow of vapor iromone section or compartment to another. The level of theliquid in the various compartments can be controlled by raising or lowering the high. vacuum end of the pump by means of adjusting element 40, and the liquid in each compartment is heated by a heating element ll which is thoroughly lagged with insulating material 42. Heating element 4| is preferably divided into a number of sections so that the'temperature in the boiler-of each compartment, .A, B, C and D can be separately controlled. Numeral 43 designates a casing substantially concentric withmain pump casing I and fastened to plate 5 and flange 4.- Casing 43 serves as a jacket for the circulation of cooling fluid into contact with the main pump casing during operation of the pump. Fluid is circulated-by introduction through conduits (not shown) locatedat the low and high vacuum'ends thereof. v Referring to Figs. 3 and 4, numeral 53 designates a main-pump casing having a cylindrical provided with fractionating rings 52. The baseof 53 at the high vacuum end is'raised at 55 as shown,-to form a dam for the pump fluid in the reservoir.- An element 51 having the form of a section of a cone is split at the base to form supporting ribs 9 and i6 and is located inside' the main casing 53 and integral therewith- The taper of section. 51 is such that the distance between it and the walls of section 53 is smaller at the low vizcuum, than at the high vacuum end in order toio'rm jets 26, 21 and 28 of progressively increasing .area in accordance with approved condensation pump jet practice. The

low vacuum end of internal casing 51 is closed by plates 20 and-2| which are'integral with end plate 5 whichl closes the low vacuum and oi. casing 53 and to which is connected the conduit 6 leading to the backing pump. 7 3

Referring to Figs. 5, 6, 7-and 8 numeral 66 i designates a main pump casing which is-slightly .conical in shape, the narrower end beinglocated at the low vacuum side of the pump. The base of from the'high vacuum zone'to the low vacuum zone is cut away and extended to form an elongated reservoir '62 having walls 63 and .64 and base 65. The approximately cylindrical element 3 has its base cut away in a position corresponding to the location of reservoir 62 and is separated into a plurality of compartments by partitions l3, l4 and I5 which extend to the base 650i reservoir 62 as shown. The bottom edges of partitions l3 and I5 are provided with a series of openings 33 and 35, but the bottom edge of partition il extends -to the base plate 65 of the reservoir and may be integral therewith. The base of cylindrical casing 8 is provided with two supporting extensions 66 which are integral with the lower portions of partitions l3, l4 and i5 and which are separated from the walls 63 and 64 of the reservoir 62 by spacers 68 which are preferably thicker at the 'upper than at the lower end so that a wedgeshaped space exists between the walls 63 and 64 of the reservoir and of the supporting extensions 66. The bottom edges of supporting members 66 are provided with a series of nicks or openings 63 so that the wedge-shaped space is connected to reservoir 62. Plate ll extends to the base plate 65 of'the reservoir 62 and substantially prevents the flow of liquid from the boiler of B to that of C. The base of partitions l4 and I5 are restricted to form a clear passage-' way 80 from the reservoir of compartment B to that of compartment D, A plate 16 integral which is capped by element II to form the jet 12. It will be noted that the restricted throat I3 is formed so that the jet 12 has a greater diameter. A series of baifles H and 'li are located in the high vacuum end oi. casing 60 and near the base of bailles 15 is located a conduit 16. The low vacuum end of the pump casing 60 is connected to and integral with a flange l1 which is connected to conduit 6 which leads to a backing pump. A packed adjustment screw 8|, which is also sealed in oil, by a sealing liquid introduced through cup/82, is connected to plate 18 by integral unit 83 and permits one to slide the assembly 8 back and forth to obtain the proper jet clearances between 3 and conical casing 60. e

Referring to Fig. 9, numerals 66 and 31 designate the wall and cap of an umbrella type jet,

12, the vapor for operation of which is supplied by conduit 86 which is flared at I! and integral with the .wall of 36, and which connects with rectangular box-like extension 36 asillustrated. The walls SI and 32 of ill! extend into thepump fluid reservoir, and separate the boiler into a compartment in-substantially the same way as partitions. l4 and I5 of Fig. 1 separate the boiler into an individual compartment; The compartment thus segregated is analogous to compartment C in the other flgures and is so labeled.

The bottom edges of walls 3! and 32 extend to the base of the boiler and are provided with holes 93 and 94 inorder to allow passage of pump liquid from the boiler of compartment B into section 9|! and thence into the reservoir of compartment D. The reservoir in section D'com-.

municateswith 'the openings 3| in the pump section I, so that vapors travel therefrom'through are slightly elevated from the base'to allow free flow of liquid from one section toanother but prevent substantial turbulence thereof. Along the walls of chamber I01 are located a plurality of trays I III which are closed at one end by plates III and are integral with plate at the other end.

In Fig. 12,reference numeral I26 designates a cylindrical main pump casing in the base of which is located a reservoir I29 and a body of pump fluid 32 as in Fig. l. Partitions I3, I4 and I5 are located in the internal casing-8 substantially as previously described and serve toseparate the boiler or reservoir into compartments and deliver separate vapor streams to the individual jets 26, 2'! and 28 by way of openings 29, 30, and 3i.' The low vacuum end of casing 8 is closed bypartition 25 which extends to the base of main pump casing I28; and is provided conventional condensation 'pump consisting of a jet' I35, condenser I36 and boiler I3'I. The con-- denser I36 is also providedwith a series of reentrant or iractionating trays i322 which terminate in a conduit I39 which leads to a backing pump. The intake alembic I36 and the boiler I31 are connected by conduits I49 and "I to a pumping liquid reservoir M32. Pumping compartment C in casing I29 is connected with the base of reservoir I42 by conduit I 53 which is provided with a drop counter I.

In Fig. 13, numeral I 4&designatesa cylindrical conduit bent at right angles to form an extension I49 at one end and extension I50 at-the other end. Section I is provided with a series of fractionating trays I55 which connect to a conduit I52 which is, in turn, connected to a backing pump inot shown). -In the walls of section I49 are formed a series of trays I53, the lower one of which connects to a conduit I54 communicatin'g with a reservoir I55. Reservoir I55 is partially filled with pump fluid 32,fwhich may be introduced through conduit lil provided with valve I56. The base of reservoir I55 connects to conduit I59 in which is located a magnetically tion I49. Conduit I61 is provided with a spiralled section which is jacketed'by I66 through which and no. Boiler m is located centrally within H8 is provided with a closed base "I which is integral with the bottom of boiler I66. A plate I19 having a flared edge I80 is integral with the the inside edge with a series of-openings l6! which allow the ilow .of pump liquid therethrough but "which substantially prevent the escape of vapor generated inside the boiler. Boiler I66 is provided with a heating element I82 along its base, including theportion I83 projecting outside the portion covered by the cones.

In operation employing the apparatus of Fig. 1, pump fluid is introduced to approximately to the level indicated and screw 40 is adjusted so ihat the liquid is at a suitable level-in each of the compartments. Conduit I. is connected to the chamber-to be evacuated, and conduit 6 is connected to the backing pump which is put into operation.' When the pressure in the system has action takes place in compartments B, C and D.

Vapors passing through mushroom jet I2 entrain g'as diffusing from the chamber to be evacuated through conduit I and force them into the vapor jet issuing from 24R Vapors from jet I2 are condensed upon the inside wall of'main casing 3 and flow thence down into the boiler in the base of the casing, passing between the wedgeshaped passage formed between supporting extensions IO and the inside walls of 3. Vapors issuing from jet 24 force gases pumped from jet I2 to jet 23 and then condense in a similar manner on the inside walls of easing 3 in-the neighborhood of the jet and pass down the walls back into the boiler of section C. Similar-action takes place with the vapors issuing from the jets'23 and 22.

During the operation of the pump, higher vapor pressure'pump vapors will tend to persist for a longer time before condensing on the walls of 3, while the lower vapor pressure pump vapors will condensealmost immediately and will directly return to the boiler compartment from which they came. The lighter vapors will tend to pass into thenext jet before condensation and there will, therefore, be a tendency for the pump to thrust light or high vapor pressure constituents towards the low vacuum end of the pump or into compartment A, while the successively lower vapor pressure constituents will immediately condense and return to the original boiler and thus become segregated successively in compartments B, C and D. A similar fractionati'ng efiect takes place in the boiler. Light constituents are vaporized and pass through the jet, 22. The unvaporized less volatile constituents pass through the cooling fluid is circulated by way of conduits I69 if Y a series of cones us, no, Inseam; Cone openings 33 into section B where the next lower vapor pressure constituents are vaporized "and pass through jet 23. The remaining constiuents pass through openings 34 into compartment C where the next lowest vapor pressure constituents are removed and pass through jet 24. The lowest vapor pressure constituents of the pump fluid are therefore vaporized in compartment D and exert their effect in the jet I2 which operates under the highest vacuum and they are, therefore, employed at the point where a low vapor pressure pump fluid .free of undesirable lighter constituents can perform the best' pumping action. "By

thus separating the pump fluid into constituents of progressively decreasing vapor' pressure and causing each constituent to operate at its appropriate pressure, the higher vapor pressure portions are caused to do most of the pumping at the higher pressure, while the lower vapor pressure fractions are allowed to simmer gently at the high vacuum end where they reduce the constituents can be properly selected; The fraction'al condensation and separate return of con-' densate is decidedly advantageous, but pumps in which all condensate is returned to the first compartment' or is otherwise mixed and returned to the boilel are considered as part of my invention if they embodythe features of jet and boiler arrangement and design herein disclosed.

The staggered baflles 18 shown in the base 01' the boiler of Fig. 1, smooth the flow of pumping liquid and assure vaporization of desired components before it reaches the next vaporizing compartment. Such baiiles can be employedwith advantage in the apparatus illustrated in the other figures. I

The apparatus illustrated in Figs. 3 and 4 is operated in somewhat the same manner as that of Fig. 1." The boiler, however, is substantiallyv horizontal and is not shown as being subject to regulation by tilting. The flow ofliquid from compartment (A to compartment 0 takes place .in substantially the .s'ame manner and the tilting wall 53 is greater than the distance between jet 26 and wall 53. In this way the clearance of the jets increase progressively from the low to the high vacuum 'side of the pump and the efficiency .is therefore increased. The pump illustrated in these figures is devoid of a jet extended into the high vacuum end as was shown in Fig. -1. The use of such a jet is preferred since it is'com-- pletely circular and enables ejection of gases on all sides ofthe jet operating under the highest and conduit 6 to a backing pump, which is started and the system evacuated to a sufliciently low value, at which time pump fluid in the reservoir 62 is heated by a heating element (not shown). The lighter components of the pump-fluid are vaporized in the boiler section Abetween partitions 28 and 13. The vapors pass from the boiler up into the cylindrical space between these two partitions, and out through openings 28 and are deflected as avigorous vapor stream towards pump 'fluid deprived of its more volatile constituents flows through the openings 83 in the bottom edge of partition. l3 into theboiler compartment by the base 85 of the boiler and walls 61 and I8 l the low pressure end of the pump by-jet 28.- The at the base of section B. vaporization oi! the and passes into the boiler of section. D. The liquid, therefore, by-passes section C and goes directly from the boiler of section B into the boiler of section D. In the boiler of section D vaporization of the best portion of the pump fluid 5 takes place and the advantages of its pumping action availed of in the high vacuum jet 12. The pump fluid deprived of these constituents then' passes through the openings in the bottom edge of partition l5 into the boiler under 10 section C. Here vaporization of the least volatile constituents takes place and they pass out through openings I3 and jet 24. The boiler under section C serves as a sumpfor the non-volatile constituents of the pump fluid. The jet operatl5 ing under the highest vacuum is thus supplied with the best portion 01' the pump fluid, which is substantially free of non-volatiles, while that containing the non-volatile constituents, as well as useful low vapor pressure pumping constituents 20 is employed in the next highest pressure jet.

The fractionating effect exerted by the condensing walls of 'main casing 88, further aids in the separation of the constituents of the fluid as explained in connection with Fig. .1. I flows down the walls of 68 into the wedge-shaped space between walls '64 and supports 68 and thence backinto the boiler 82. During operation some of the pump fluid vapors may tend to difluse backwards towards the chamber being so evacuated. The two series of baflies I4 and I8 serve to condense such vapors. Those condensing in baflies I4 flow along the bottom of and pass back=into the boiler at the base of compartment D. 'I'lrwse condensed by baflle I5 flow to 35 are withdrawn through conthe base thereof and duit 15.

' In Fig. 9 isillustrated a modification of compartments C and D illustrated in Fig. 5. The

last jet 12 is supplied by vapor from compartment 0 C. The ivapors travel from the boiler of compartment C up through conduit 88 and are ejected through jet 12. The entire conduit 88 is surrounded and warmedby vapors from the boiler of compartment D which supplies compartment D and jet 28. The vapors from jet I2 are the lowest vapor pressure constituents of the pump fluid and, therefore, have a decidedly greater tendency to condense before reaching the jet even at somewhat elevated temperatures. Since the conduit supplying the jet I2 is entirely surrounded by vapors from the boiler supplying compartment D,

to the chamber to be evacuated and conduitt is connected to the backing pump which is put into operation. Pump fluid is heated by the element 4| and is partially vaporized in compartment I81. Light, or high -vapor pressure constituents, are

vaporized and'tend to condense in the fraction ating trays H8. *Fractionation of: the vaporized pump fluid takes place in these trays and the lower vapor pressure constituents are returned to the boiler. The pump flpid deprived-oi' these undesirable constituents which haye too high a vapor pressure for useful pumpinglrthen passestlnbugh openings I88 in the bottom. e'of partition 28. In compartment A the lig test useful constituents are vaporized and pass out through f jet 28.- The successively lower vapor pressure 15 Condensate 25 constituents are then vaporized in compartments B and C as the fluid passes successively therethrough as explained above. The fractionating trays 'I I II enable the use of a pump fluid which has not been refined to remove any or all of the lighter constituents which would have an adverse efiect on the pumping action of jets 26, 21 and 28.

means not shown) The operation of jets 26, 21 and 26 of Fig. 12 is substantially the same as described in connection with the apparatus illustrated in Figs. 1 and 3. The high vacuum end of I28 is connected to the system to be evacuated and conduit I39 is connected to a backing pump and the entire system is evacuated to a low pressure at which the condensation pump can operate. The pumping fluid in boilers I31 and I29 is then heated by heating compartment C passes through openings III and issues through jet 28 entraining gases diffusing from the chamber to be evacuated. Condensate from the wallsof I28 flow back into the boiler. The gases entrained by jet 28 are entrained in vapors from jet 21 and finally by vapors from Jet 26.

flows down the walls of I34 and passes successively through the boilers of compartments A, B

and C and finally overflows into the conduit I43 and is returned to reservoir I42. Reservoir I42 holds the main supply of pump fluid and allows it to flow into boiler I31 by way of conduit I4I at a rate corresponding to that at which it is vaporized from the boiler. In this way only small amounts of the pump fluid are heated at any time and decomposition is thereby" considerably tently causing thepump plunger I66 to move up.

decreased. Conduit Mil-connects the reservoir I42 with the source of vacuum so thatthe pressure maintained therein will be substantially the same as that in the rest of the system. c

In operating the apparatus of Fig. 13, conduit I52 is connected to'the backing pump and conduit I49 to the system to be evacuated. Reservoir I55 is filled with pump fluid to approximately the level shown and the system is evacuated by the backing pump. Solenoid I63-is actuated intermitand down, forcing'liquid through conduit I65 into boiler I66. In the fore part I83 of the reservoir, the pump fluid is heated and freed of its most ;volatile constituents which pass up the conduit I56 and are condensed and retained in the fractionating trays I5I and may be removed there-' from by way of conduit I12 at appropriate inter vals. The pump fluid free of volatiles then flows through the openings I8I in element I19 and is vaporized during its passage from conical jets I15 to I18. The higher vapor pressure constituents of the pump fluid pass out through the jet formed by cone I15. The next lower vapor pressure constituents pass out through jet I16, and so forth. The residue passes through opening I84 and overflows into conduit N51, is cooled to anappropriate temperature in cooler I66 then overflows from one trough I53 to another. The liquid finally flows through conduit I54 back into reservoir I55. The purpose of; washing the walls at I53 is to remove gases absorbed thereto; or to remove pump fluid whichhas absorbed gases dur- Vapor from the boiler of r ing a previous shut down'". The pump fluid picks up these materials and conveys them to the low pressure 'side of the pump, namely to the low pressure end I83 of boiler I66, where the 'gases and volatiles are released and withdrawn into the backing pump and are prevented from interfering with the higher vacuum stages of the pump. The reservoir I55 permits heating 'of only small amounts of the pump fluid as explained in describing the apparatus of Fig. 12.

While several of the drawings illustrate pumps having an extended or projecting high vacuum jet, such as jet I2 in Fig, 1, and jet 12 in Fig. 5, it will be apparent that this same expedient can be employed with the other types of pumps illustrated, and that the use of such jets will'in many cases be necessary or desirable. The extended jet illustrated in Fig. 5 is preferred, since the particular construction shown enables a higher pumping rate. Any analogous construction gives the high pumping characteristic of this type of jet as long as the walls delivering the vapor to the mushroom jet are constricted at a point immediately below the mushroom jet or, in other words, is constricted below the point at which the vapors issue from the jet. It is believed that the high pumping rate obtained by a jet constructed in this manner is dueto'the fact that the vapors issuing therefrom can expand both inwardly toward the axis of the tube delivering thb jet vapor as well asvoutwardly from the cap 1|. An advantage of using a jet projecting back of the main casing 8 is that vapors condensed on the walls of the main pump casing in that area will be swept by the jet vapors back into the boiler of the main pump. Such action is of considerable advantage when gases are absorbed in the pump fluid in that area during shut down of the pump. It will be apparent that many changes and modifications can be made in the apparatus illustrated without departing from the spirit or scope .of my invention. For instance, all of the internal jets can be constructed as one removable unit, as illustrated in Figs. 1 and 5, including the partitions, main casing, etc. and can be inserted inside the main pump casing. Such construction would simplify the problems of dismantling and assembling the pump when necessary for cleaning. The apparatus illustrated in Fig. 1 is most easily constructed since most of the elements are cylindrical. Also cylindrical elements would withstand the pressure of the atmosphere betterthan an irregularly shaped pump casing. The simplest boiler construction is shown in Fig. 1, but it has the disadvantages that considerable heat conduction between the boiler and the jets and ,walls of the condenser takes place. The extension of the boiler to the outside ofthe pump as illustrated in 'Fig. 5 considerably decreases this harmful conduction of heat and 'WOI.11d, therefore, be preferred in many cases. .However, the difficulties in construction are much greater.

' It is'desirableto have the clearance between the jets and the main casing progressively increase from the low to the high vacuum side of thesignificance. Also, the size and number of reand that the number illustrated has no particular entrant rings can be varied to enable the segregation of volatiles with-return of useful constituents. Any suitableconstruction materials such as glass or sheet or. cast metals may be used.

The apparatus illustrated has the decided ad vantage that a mixed pumping fluid can'be used and that the diflerent vaporpressure constitucuts of the pump fluid are segregated and caused to perform their pumping action at an appropriate position in the pump. Non-volatile constituents are segregated and prevented from e'xerting harmful action upon the entire body of the pump fluid.. Very volatile constituents, unsuitable for pumping action are vaporized from the pump fluid, and prevented from returning thereto The problem of employing annular jets, or jets of similar shape to-the main casing, with a fractionating boiler which is approximately horizontal is overcome by the const ction shown. Due to the fact that such jets operating on all sides of the casing can be employed, the efllciency and capacity of the pumps are greatly increased;

By means of the extended rear jet, a completely annular jet is provided at the highest vacuumzone of the pump and maximum pumping action at this important place is, therefore, possible.

The app -r ms illustrated furthermore is decidedly advantageous since it enables fractionation of .the pump fluid vapors issuing from the jets as well as fractionation of fluid in the boiler. As. explained above, vapors issuing from the lowest vapor pressure jet are more or less fractionally condensed, the lowest vapor pressure constituents immediately condensing on the walls of the .pump casing and returning to the boiler compartment Irom which they originated. Any lighter constituents formed during the vaporiza- .tion'or accidentally getting into that particular boiler are not condensed until they reach the next highest vapor pressure jet where they areentrained and, if of proper vapor pressure, are condensed with the vapors of that jet and returned to the boiler from which that particular vapor-originated. Atwo-fold separation andsegregation of the pump fluid into constituents of progressively decreasing vapor pressure therefore takes place, and the individual constituents are 7 having jets approximately the same geometrical vaporized and caused to perform a pumping action in the most appropriate position in the pump. While this construction'has obvious ad-- vantages, my invention is notlimited to this particular feature and it is to be understood that iractionating pumps free of such features, but

form as the main casing, which 'may be circular,

templated as being within elliptical orpolyhydric in cross section, are con-- the scope of my invention.

What I claim is: Y L

1. A condensation pump adapted to employ an organic pumping fluid comprising in combination, a main pump casing the longitudinal axis of which is approximately horizontal, adapted to be connected at the high vacuum end to thereceptacle to be evacuated and at the other or low vacuum end to a backing pump, a plurality of jets located in series in the main casing and having substantially the same geometrical form as, and approximately co-axial with the main casin a boiler adapted to convert the pump fluid into separate vapor streams or compounds of w '-,progressively. decreasing vapor pressure, means 'for conveying the lowest vapor pressure stream to the jet operating under the highest vacuum, means for conveying the progressively increasing vapor pressure streams to each succeeding jet operating at successively higher pressures and means for condensing the pumping vapors and returning the condensate to the boiler.

2. A condensation pump adapted to employ an organic pumping fluid which comprises in combination a main pump casing, the longitudinal axis of which is approximately horizontal, adapted to be connected at the high vacuum end to the receptacle to be evacuated and at the other or low vacuum end to a backing pump, an approximately horizontal series of jets located in the ma casing and having substantially the same geometrical form as, and approximately 00- axial with the main casing, an approximately horizontal boiler located in the bottom of the main pump casing and divided into a plurality of vaporizing compartments by partitions whichallow pump fluid to slowly flow from one compartment to another but which substantially prevent the flow of vapor from one compartment to another, means for conveying the lowest vapor pressure stream generated in the boiler comparts ments to the jet operating under the highest vacuum and means for conveying the increasing vapor pressure streams generated in the other compartments to each succeeding jet operating at successively higher pressures and means for condensing the pumping'vapors and directly and immediately returning substantially all of the partment from which it was vaporized.

3. A condensation pump adapted to employ an organic pumping fluid which comprises in combination a main pump casing, the longitudinal axis of which is approximately horizontal, adapted to be connected at the high vacuum side to the receptacle to be evacuated and at the low vacuum side to a backing pump, an approximately horicondensate fromeach jet to the vaporizing com zontal series of jets located in the main casing and progressively decreasing in cross-section from the low to the high vacuumside of the pump and having substantially the same gecmetrical form as and approximately co-axial with, the main casing, an approximately horizontal boiler located in the bottom of the main casing and divided into a plurality of vaporizing compartments by partitions which allow pump fluid'to slowly flow from one compartment to another, but which prevent the flow of vapor from one compartment to another, means for con- 1 veying vapors generated in the boiler compartment nearest the high vacuum side of the pump to the jet operating at the highest v'acuumand means connecting the successive boiler compartments to the successive jets operating at successively higher pressures, means for condensing the vapors issuing" from each jet and for directly. and immediatelyfreturning substantially all of the condensate from each jet to the boiler compartment from which it was vaporized.

4. A condensation pump adapted to employ an means for conveying the lowest vapor pressure stream to the jet at the high vacuum end of the pump, means for conveying the progressively increasing vapor pressure streams to each jet operating at successively higher pressures and means for condensing and returning condensed o fluid to the boiling and fractionating means.

5. A condensation pump adapted to employ an organic pumping fluid comprising in combination a main pump casing the'longitudinal axis of which is approximately horizontal, adapted to 'be-connected at the high vacuum side to the receptacle to be evacuated and at the other'orlow vacuum side to a backing pump, a plurality of approximately annular jets located, inside the main casing and ad'aptedto pump inseries'an progressively increasing vapor pressure streams to each jet operating at successively-higher pressures and means for condensing the pumping vapors and directly and immediately returning thecondensate from each jet to the vaporizing compartments from which they were derived.

'6. A vacuum pump of the condensation type adapted to employ an organic pumping fluid, comprising in combination, a main pump casing adapted to be connected at the high vacuum-end to the receptacle to be evacuated and at the other or low vacuum end toa backing pump, a plurality of jets located inside the main casing and adapted to pump in series, a plurality of vaporizing compartments adapted toconvert the pump fluid into separate vapor. streams of compounds of progressively decreasing vapor pressure, means for conveying the lowest vapor pressure stream,

to the jet nearest the high vacuum end of the pump, means for conveying the progressively increasing vapor pressure streams to each succeding jet operating at successively higher pres- ,.sures, condensing means and means for directly and immediately: returning substantially all of' the-useful condensate to a vaporizing compart- I -ment the same as or contiguous to that tromwhich it was vaporized.

7. A vacuum pump of the condensation type I adapted to employ an organic pumpingfluid comprising incombination a cylindrical main v pump casing, the longitudinal axis of which is approximately horizontal, adapted to be connected at the high vacuum -end to the receptacle to be evacuated and at the other or low vacuum end to a backing pump, a plurality of annular jets located inside the main casing and substantially concentric therewith and adapted to-pump in se-. ries, a plurality of vaporizing compartments adapted to convert the pump fluid into separatevapor streams of compounds of progressively decreasing vapor pressure, means for 'conveying thev lowest vapor pressure stream to the jet nearest' the high vacuum end of thepump, means for conveying the progressively. 1 increasingly vapor pressure streams to each succeeding jet operating at successively higher pressures, condensing means for each jet and means for directly and immediately returning substantially all of the useful condensate to the vaporizing compartment from which it was vaporized.

8. A condensation pump adapted to employ an organic pumping fluid comprising in combination, a cylindrical main pump casing the longitudinal axis of which is'approximately horizontal one end of which is adapted-Ito be connected to the receptacle to be evacuated and the other to a backing pump, a second approximately cylindrical casing of smaller diameter located inside the main casing and substantially concentric therewith, aseries of annular jets located on the periphery ofthe second casing, an approximate- .ly horizontal boiler located in the base of the main casing and of approximately the same length as the second casing, spaced partitions in the boiler dividing it into compartments corresponding in number and positionto that of the jets, the partitions allowing slow flow of liquid from one compartment to another, but substantially preventing flow of vapor from one compartment to another, means for conveying vapor 1 from each boiler compartment to its respective jet and means for condensing the jet vapors and directly and immediately returning substantially all of the useful-condensate to the same or closely adjacent boiler from which it was vaporized. r

9. Acondensation pump adapted to use an organic working fluid comprising in combination a cylindrical main pump casing, the longitudinal axis of which is approximately horizontal adapted at one end to be attached to the chamber to be evacuated and at the other end to be attached to a backing pump, a second approximately cy-. lindrical casing located inside the first casing and approximately concentric therewith, a boiler in the base of the first casing and of approximately the same length as the second casin a plurality of partitions inside the second casing which divide it into a plurality of approximately cylindrical compartments, corresponding partitions in the boiler which permit slow flow of pumping liquid from one boiler section to the other, but which substantially prevent passage of vapor from one section to the other, annular jets locatedon the outside walls of the. second casing at each compartment and so located-as to propel pump vapors in the direction of the backing pump, means for conveying pump vapors gener-: ated in the boiler compartments to the correspending-cylindrical compartments in the second casing and thence into the corresponding jets located on the surface thereof, means for cool-, ing the walls of the main pump casing, andmeans for directly and immediately returning substantially all the .pump liquid condensed on the inside walls of the main pump casing to the boiler compartments densation. V V

10 A vacuum pump adapted to employ an organic pumping fluid comprising in combination means containing an organic fluid for producing a stream of pumping fluid vapor, a condenser, a jet through which the vapor stream flows to the adjacent to the area of concondenser, a conduit connecting the chamber to ing means is small compared with the volume of adapted to convert the pump fluid into separate vapor streams of compounds oi decreasing vapor pressure, means for conveying the lowest vapor pressure stream to the Jet at the high vacuum and of the pump, means for conveying the progressively increasing vapor pressure streams to each jet operating at successively higher pressures. and means for condensing and returning them to the boiling and iractionating means, the jet at the high vacuum side of the pump being an umbrella type jet. which is supplied with actuating vapor by a chimney characterized by the fact that the outside of the chimney in the vicinity of the jet gradually decreases in diameter in the direction in which the vapors pass from the jet. v

I KENNETH C. D. HICKMAN. 

